Various substituted benzimidazoles are known to be useful as herbicides. U.S. Pat. No. 3,325,271 describes the use as herbicides of a broad class of substituted benzimidazoles in which there is at least one substituent on the aromatic ring or at the 1- or 2-position of the molecule. The aromatic substituents may be selected from nitro, halo, lower alkyl, lower alkoxy and halo-lower alkyl. U.S. Pat. Nos. 3,901,910 and 3,954,438 describe a specific group of 5-trifluoromethyl-7-aminobenzimidazoles which have herbicidal activity.